Fibrous structures comprising pillows and knuckles are known in the art. However, such pillows within the known fibrous structures have exhibited similar heights not differential heights.
It has been found that consumers of fibrous structures that comprise similar height pillows desire improved properties, such as softness, strength, absorbency, cleaning, flexibility, and compressibility.
It has been found that the 3D patterns of the known fibrous structures, for example as shown in FIGS. 1A and 1B, which illustrates a patterned molding member that imparts a 3D pattern of semi-continuous pillow and semi-continuous knuckles to a fibrous structure fails to retain sufficient Surface Void Volume during use by consumers to provide consumer desirable cleaning performance after bowel movements. As shown in FIGS. 1A and 1B, the known patterned molding member comprises a molding member 10, for example a through-air-drying belt. The molding member 10 comprises a plurality of semi-continuous knuckles 12 formed by semi-continuous line segments of resin 14 arranged in a non-random, repeating pattern, for example a substantially machine direction repeating pattern of semi-continuous lines supported on a support fabric (“reinforcing member”) comprising filaments 16. In this case, the semi-continuous lines are curvilinear, for example sinusoidal. The semi-continuous knuckles 12 are spaced from adjacent semi-continuous knuckles 12 by semi-continuous pillows 18, which constitute deflection conduits into which portions of a fibrous structure ply being made on the molding member 10 of FIGS. 1A and 1B deflect. The resulting fibrous structure being made on the molding member 10 of FIGS. 1A and 1B comprises semi-continuous pillow regions imparted by the semi-continuous pillows of the molding member 10 of FIGS. 1A and 1B and semi-continuous non-pillow regions, for example semi-continuous knuckle regions imparted by the semi-continuous knuckles of the molding member 10 of FIGS. 1A and 1B. The semi-continuous pillow regions and semi-continuous knuckle regions may exhibit different densities, for example, one or more of the semi-continuous knuckle regions may exhibit a density that is greater than the density of one or more of the semi-continuous pillow regions.
One problem with known fibrous structures is that the known fibrous structures comprise pillows that exhibit similar heights and thus do not comprise differential height pillows, for example two or more pillows that exhibit differential pillow height
Accordingly, there is a need for a fibrous structure, such as a sanitary tissue product, that comprises two or more pillows that exhibit differential pillow height.